Spore contamination of Tilletia tritici in seed lots as affected by field disease incidence

Seed lots normally become contaminated by spores of the seed borne common bunt (Tilletia tritici) during harvest of fields with infected plants. To demonstrate the relation between the number of infected plants in the field and the resulting number of spores in the harvested seed lot, a fixed number of infected tillers were placed in uncontaminated wheat fields. Two field experiments show that the number of spores in the seed lot is proportional to the number of infected plants in the field. Only 3% of the spores from the infected plants in the field end up in the seed lot after harvest with a combine harvester. However, only few spores in a seed lot is enough to establish infection in the next year field, and with a threshold of 10 spores/g seed which is the current threshold for untreated seed in Denmark, less than 1 infected tiller per 1000 m2 can be accepted in a field aimed for propagation

Modelling root distribution and nitrogen uptake

Plant soil and atmosphere models are commonly used to predict crop yield and environmental consequence. Such models often include complex modelling modules for water movement, soil organic matter turnover and, above ground plant growth. However, the root modelling in these models are often very simple, partly due to a limited access to experimental data. We present a two-dimensional model for root growth and proliferation. The model focuses on annual crops, and attempt to model root growth of the crops and its significance for N uptake from different parts of the soil volume

Opto-fluidic third order distributed feed-back dye laser

This letter describes the design and operation of a polymer-based third order distributed feed-back (DFB) microfluidic dye laser. The device relies on light-confinement in a nano-structured polymer film where an array of nanofluidic channels is filled by capillary action with a liquid dye solution which has a refractive index lower than that of the polymer. In combination with a third order DFB grating, formed by the array of nanofluidic channels, this yields a low threshold for lasing. The laser is straight-forward to integrate on Lab-on-a-Chip micro-systems where coherent, tunable light in the visible range is desired.Comment: 4 pages, 3 figure

A model analysis on nitrate leaching under different soil and climate conditions and use of catch crops

The use of crops and catch crops with deep rooting can strongly improve the possibility of retaining nitrate-N that will otherwise be leached to the deeper soil layers and end up in the surrounding environment. But will it always be an advantage for the farmer to grow a catch crop? This will depend on factors such as soil mineral nitrogen level, soil water holding capacity, winter precipitation, rooting depth and N demand of the scceeding crop. These factors interact, and it can be very difficult for farmers or advisors to use this information to decide whether growing a catch crop will be beneficial. To analyse the effect of catch crops under different Danish soil and precipitation conditions, we used the soil, plant and atmosphere model Daisy

Simulating Root Density Dynamics and Nitrogen Uptake -Field Trials and Root Model Approach in Denmark

Plant soil and atmosphere models are commonly used to predict crop yield and associated environmental consequences. Such models often include complex modelling of water movement, soil organic matter turnover and above ground plant growth. However, the root modelling in these models is often very simple, partly due to a limited access to experimental data. Here we propose a root model developed to describe root growth, root density and nitrogen uptake. The model focuses on annual crops, and attempts to model root growth of different crop species and row crops and its significance for nitrogen uptake from different parts of the soil volume